ML20104B826
| ML20104B826 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 06/30/1992 |
| From: | Talwani P SOUTH CAROLINA, UNIV. OF, COLUMBIA, SC |
| To: | |
| Shared Package | |
| ML20104B827 | List: |
| References | |
| 92-2, NUDOCS 9209160225 | |
| Download: ML20104B826 (19) | |
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{{#Wiki_filter:--_- _ _ - _ _ _ _ _ _ _ ___ ____ a , TECHNICAL REPORT 92-2 SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION FOR THE PERIOD APRIL JUNE 1992 BY PRADEEP TALWANI Principa). Investigator DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTli CAROLINA COLUMBIA, SC 29208
, CONTRACT NO. N574984 hhR 0 000 95 R PDR
TECHNICAL REPORT 92-2 SEISMIC ACTIVITY NEAR THE V.C. SUMMER NUCLEAR STATION FOR THE PERIOD APRIL-JUNE 1992 BY PRADEEP TALWANI and KUSALA RAJENCRAN U DEPARTMENT OF GEOLOGICAL SCIENCES UNIVERSITY OF SOUTH CAROLINA COLUMBIA, S.C.29208 e
a INTRODUCrlON
-Analysis of the seismic activity near the V.C. Summer Nuclear Station in South Carolina for the period April June 1992 is presented in this report. During this I period,10 events were recorded in the vicinity of Monticello Reservoir. Four events
-._ were located. The largest two events recorded were of' magnitude ML= 1.0. One occurred on April 2 (17:14:29.62 UTC) and the other was on May 29 ( 16:54:44.12 UTC).
The seismicity during this quarter was at a very low level. SEISMIC NETWORK l LEarthquakes during this period were recordea on stations of Monticello Reservoir and South Carolina Seismic Networks. The configuration of stations utilized to
-locate' Monticello events is shown in Figure la'and station coordinates are listed in
. Appendix I. The network was fully operational during most of this quarter except for stations MR01 and MR02, which were not operational for five days in May. The operational status of the network is given in Appendix II. Since April 29,- the events from Monticello Network are also recorded digitally on the PUFFIN unit, in addition to the existing facility of analog recording on the tape recorders. The digital data retrievable on the computer provide more accurate P and S arrival times, Sample traces : for the event on April 29, reconstructed from the digital data are presented in Figure Ib.
" DATA ANALYSIS-Hypocentral locations have been determined using the computer program HYPO 71-(Lee and Lahr,1972). The velocity model used in the earthquake locations is given !n Appendix III. The format of the output is given in Appendix IV. The event magnitude was determined from the signal duration at JSC using the following relation:
ML = -1.83 + 2.04 Log D,
.where D is the signal duration (seconds).
An estimate of daily energy release was determined using a simplified magnitude
- (ML) . energy (E) relation by Gutenberg and Richter (1956): . ~
Logio E = 11.8 _+ 1.5 M L-1
- . aa.
( 4 OBSERVED SEISMICITY DURING APRIL-JUNE,1992 { During this period,10 carthquakes were recorded, of which 4 were located (Figure 2; i Appendix V). Only one of the :ocated events was of B quality and the rest were of C l or D quality. There were two events of magnitude ( ML=1.0 ), one on April 2 (17:14:29.62 UTC) and one on May 29 ( 16:51:44.12 UTC). The other two locatable events were of magnitudes ML = 0.8 and 0.2, which occurred on April 29 and May 21, respectively. The remaining events during this period were generally of short I duration (less than 10 see) with an S-P time 6f 0.25 to 0.9 see at JSC, Mn07 and MR10 (Appendix VI). The located seismicity was scattered, with three events occurring to the north of the lake. Only one of the located events on May 21 ( Mt =0.2) occurred in the middle of the lake where sore activity was reported during the last quarter also. The long term decline in seismicity observed at Monticello is continuing (Figure 3). The seismicity at Monticello seems to have leveled off since 1985-1986 _(Figure 4). CORRELATION OF WATER LEVEL WITH SEISMICITY Monticello Reservoir is a pumped storage faci!Ity. Any decrease in the reservoir level associated with power generation is recovered when water is pumped back into the reservoir. There can be normal variations up to five feet per day between maximum and minimum water levels. The water level has been monitored to see if there is any correlation between the daily or seasonal changes in the reservoir level and the local seisnilcity. Water levels are compared with seismicity in Figure 5. The top panel shows the average water level; the error bars show the maximum and minimum _ water levels each day. The second panel shows the change in water level from day to day. The number of events per day and the log of energy released are shown in the lower histograms. These charts inciude all reported carthquakes listed in Appendices V and V1. The average water level, daily changes in water level, number of earthquakes and energy release are given in Appendix VII. No systematic
. correlation was observed between the seismicity and reservoir level fluctuations.
CONCLUSIONS The data collection and interpretational facilities for the Monticello Network have been further improved by digital recording of the data. The level of seismicity recorded during the second quarter of 1992 was generally of a low level. Of the ten recorded events only two were of magnitude ML21.0. No systematic correlation was observed between the reservcir level fluctuations and the seismicity. 2 4
1 n ~ REFERENCES Gutenberg, D. and Richter,C.F. (1956). Magnitude and energy of earthquakes, Ann. Geof. 9,1-15. Lee, W.HK and Lahr, J.C. (1972). A computer program for determining hypocenter,
. magnitude and first motion pattern of local earthquakes, revisions of HYPO 71, U.S. i Geological Survey, Open File Report,100 pp.
e 3
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_l 19.5 _19.0 _18.5 _1B.O _17.5 17.0 _16.5 _16.0 _15.5 34 4 1 4 I i i i i i l 1 1 1 4 0 KILOMETERS 5 1 1 i i 1 1 Figure 2. Earthquakes located near Monticello Reservoir during the period April June,1992 ' i I 6 : 1
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- Z 0 92 107 122 137 152 167 182 Figure 5. Comparison of daily reservoir level, changes in reservoir level, number of earthquakes and the log of energy release in ergs per day at Monticello Reservoir. Error bars in the top panel indicate daily fluctuations in reservoir level.
1 9
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- APPENDIX I STATION LOCATIONS STATION LAT N LONG W JSC 3416 0'- 81 15.60' MR01 3014 ~ 81 17.74' MR02 34*11.58' 81 13.81' MR05 34 16.05' 81 20.05' MR07 34 22.23' 81 19.50' MR10 34 20.18' 81 20.25' i
A ib 10
r APPENDIX 11 SEISMIC STATION OPERATIONAL STATUS
. APRIL-JUNE 1992 STATION % DOWNTIME JSC 0 MR01 6 I MR02 6 MR05 0 MR07 0 MRIC '
0 l-e 11
Al'PENDIXIII MONTICELLO- n.ESERVOIR VELOOTY MODEL Velodty Depth to top km/sec km 1.00 0.00 5.40 0.03 l 5.90 0.18 6.10 0.46 6.30 0.82 8.10 30.00 4 12
r APPENDIX IV MONTICELLO EARTHQUAKES HYPO 71 FORMAT Column 1 Date
. Column 2 Origin time (UTC) h.m.sec.
Column. 3 Latitude (N) degrees, min. Column 4 Longitude (W) degrees, min. Column 5 Depth (km). Column 6 Local duration magnitude. Column 7 No. of station readings used to locate event. P and S arrivals from same stations are regarded as 2 readings. Column 8 Largest azimuthal separation in degrees between stations. Column 9 Epicentral distance in km to nearest station. Column 10 Root mean square error of time residuals in sec. RMS = Ri 2/No, where Ri is the time residua' for the ith station Column 11 Standard error of the epicenter in km*. Column 12 Standar.! error of the focal depth in km*. Column 13 Quality of the epicentrallocation.
- Statistical interpretation of standard errors involves assumptions which may not be met in earthquake locations. Therefore standard errors may not represent actual error limits.
Note: If ERH or ERZ is blank, this means that it cannot be computed, because of insufficient data. 8 13 l l t
APPENDIX V
, MONTICELLO RESERVOIR EARniQUAKES APRIL 1 - JUNE 30,1992 DATE . ORIGIN LAT H LONG W DEPTH MAG No GAP DMIN RMS ERH ERZ QM 920402 1714 29.62 34-22.33 81-20.66 1.00 1.02 7 281 1.8 0.15 2.9 4.5 D1 920429 1810 -2.98 34-23.60 81-17.18 4.90 0.82 7 292 4.4 0.15 3.6 2.7 D1 920521 1431 33.09 34-20.01 81-18.79 0.42 0.21 7 111 1.6 0.08 0.8 2.1 B1 920529 1654 44.12 34-24.09 81-22.80 2.79 1.02 8 333 6.1 0.07 1.2 -1.6 C1 l
I- ! ~ 14 i
4 APPENDIX VI
, LIST OF EVENTS WITH (S P)6 2.5 SEC RECORDED AROUND MONTICELLO RESERVOIR DURING APRIL-JUNE 1992 DATE STATION P-ARR. TIME S P(SEC) EP.DIST DUR (S) MAG (S P)X8.5 92 04 09 MR07 02 12 40.08 0.9 7.7 5 0. _
92 04 09 MR07 22 32 07.50 0.25 2.1 4 -0.6 92 05 20 MR10 03 10 55.00 0.25 2.1 5 -0.4 92 05 21 JSC 14 46 34.05 0.5 4.3 8 0 92 06 28 MR07 11 55 42.90 0.7 6 10 0.2 MR10 1i 55 43.10 92 OG 28 MR07 11 56 04.50 0.3 2.6 5 -0.4 I
=
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. Append 1 xvii .
- Maximum and minimum water levels, change in water level, number of carthquakes and energy release (ergs per day) at Monticello Reservoir during -
April-June 1992. Dates are given in Julian Calender. DATE WL (Max) WL4 Min) IWl(Ava) Change #of oos Log E
- .1 92 424.1 423.6' 423.9 0 0 93 424.6 423.8 424.2 0.4 1 13.33 94 424.5 421 2 423.9 -0.4 0 0
- 95 424.4 423.3 - 423.9 0.0 0 0
- 96 424.1 424.1 424.1 0.3 0 0 97 424.4 422.7 423.6 -0.6 0 0 98 425 423 424.0 0.5 0 0 99 424.4 423.3 423.9 0.1 0 0 100 424.9 423.3 424.1 0.3 2 11.44 101 424.9 422.9 423.9 -0.2 0 _0 102 -424.5 423 423.8 -0.1 0 0
=103 424.4 423.1 423.8 0.0 0 0 2 104 425 423.5 424.3 0.5 0 0 105 425 422.9 424.0 0.3 0 0 106 - 424.9 422 423.5 -0.5 0 0 107 424.2 -421 422.6 0.8 0 0 108 = 424.1 421.1 4?2.6 0.0 0 0 109 424.8 422.6 -423.7 1.1 0 -0 110 424.7 422 423.4 -0.4 0 0 111 -423.9 422.2 423.1 -0.3 0 0 112 -424 423.5 423.8 0.7 0 0 ,
113 424.7 423.6 424.2 0.4 0 0 114 - 423.9 423.3 423.6 0.5 0 0 115 423.4 422.1 422.8 -0.9 0 0 116 422.6 422.1 422.4 0.4 0 0 117 - 424.4 422.8 423.6 1.3 0 3
-118 - 424.7 423 423.9 0.3 0 0 119 424.9 423.1 424.0 :0.1 0 0 120 423.1 422.8 423.0 1.0 1 13.04
-121 422.9 422 - 422.5 -0.5 0 0 122 424 422.2 423.1 0.7 0 0 123 424.1 422.3 423.2 0.1 -0 0 124 423.4 422.4 422.9 -0.3 0 0 125 423.7 423.2 423.5 0.6 -0 0 ,
126 424.1 - 423.6 423.9 - 0.4 0 0 127 424.1 423.5 423.8 0.1 0 0 128 '423.8 423.5 423.7 -0.2 0 0 129 425 421.5 423.3 -0.4 0 0
- 130 424.9 422 -423.5 - 0.2 0 0 131 423 9 -422.8 423.4 -0.1 0 0 132 423 422.5 -422.8 -0.6 0 0 133 423.9 422.5 423.2 - 0.4 0 0 134 424.6 423.8 424.2 1.0 0 0 135 '424.6 423.3 424.0 -0.3 0 0 136 425 422.9 424.0 0.0 0 0
, 137 425 423.3 424.2 0.2 0 0 138 424.6 424.2 424.4 0.3 0 0 139 424.8 423.9 424.4 0.0 0 0
~, 140 424.2 -421.4 422.8 -1.6 0 0 141 424.2 421,7 423.0 0.2 1 11.19 142 421.4 422.8 422.1 0.8 2 12.24 143 425 423.6 424.3 2.2 0 0 144 424.9 422.1 423.5 -0.8 0 0 145 424.8 422 4'34 i -0.1 0 0 146 4254 421.1 423.1 -03 0 0 16
4
,_ 147 424.9 421.5 423.2 0.1 0 0 148 425 423.2 424.1 0.9 0 0 149 424.6 423.2 423.9 -0.2 0 0 150 424 424 424.0 0.1 1 13.33 151 424.5 423.8 424.2 0.1 0 0
- 152 422.3 422 422.2 -2.0 0 0 153 423.1 421.5 422.3 0.2 0 0 154 423.4 421.6 422.5 0.2 0 0 155 424.8 d23.6 424.2 1.7 0 O_
156 424 *22.9 423.5 -0.8 0 O_ 157 423.7 422.8 423.3 -0.2 0 0 158 423.4 422.7 423.1 -0.2- O O 159 422.9 422.2 422.6 -0.5 0 0 160 422.9 422.2 422.6 0.0 0 0 161 424.1 422.6 423.4 0.8 0 0 162 424.5 423.3 423.9 0.5 0 0 163 425 423.2 424.1 0.2 0 0 l 164 425 423.2 424.1 0.0 0 0 l 165 424.9 423.1 424.0 -0.1 0 0 i 166 424.8 422.1 423.5 -0.5 0 0 167 424.2 422.1 423.2 -0.3 0 0 168 424.7 423.3 424.0 0.9 0 0 169 425 423.1 424.1 0.1 0 0 170 424.8 421.6 423.2 -0.8 0 0 171 424.7 422.7 423.7 0.5 0 0 172 424.7 422 423.4 -0.3 0 0 173 424.7 422.2 423.5 0.1 0 0 174 424.5 422.2 423.4 -0.1 0 0 175 424.9 422.3 423.6 0.3 0 0 176 - 424.3 423.8 424.1 0.4 0 0
~
177 424.5 422.6 423.6 -0.5 0 0 178 -425 422.8 423.9 0.3 0 0 179 424.8 423.8 424.3 0.4 0 0 180 424.9 423.4 424.2 -0.2 2 12.11 181 424.1 423.4 423.8 -0.4 0 0 182 423.3 423.1 423.2 -0.5 0 0 1 ! 17 l L}}